1. Field of the Invention
The present invention relates to a lug folding apparatus for a packaging machine in which a packaging sheet, such as cellophane, polypropylene, and so forth, is applied to a box-like item, for example, such as cigarettes packaged by a packaging film or paper. More specifically, the present invention relates to an apparatus in which box-like items, fed into pockets, are continuously conveyed in a circular fashion, during which continuously conveyed packaging sheets are applied along the surfaces of the box-like items. The continuous circular conveyance is changed to a linear conveyance of the box-like items, and extended ends of the packaging sheets, protruding angularly from both sides of the box-like items, are folded along both sides thereof.
2. Background and Material Information
Heretofore, the lug folding apparatus for a packaging machine of this kind is disclosed, for example, in Laid-Open Japanese Patent Publication No. Hei 2-85109. Between a continuously rotating winding wheel, having in the outer periphery thereof a plurality of pockets at equal intervals, and an intermittently rotating tray conveyor, having in the outer periphery thereof a plurality of pockets at equal intervals, an angularly extended chain conveyor is provided which has access to a predetermined section in the outer periphery of the winding wheel and a predetermined section in the outer periphery of the tray conveyor. The chain conveyor is curved in the form of a recess and a plurality of pockets are provided thereon having the same spacing as the spacing arrangement of the pockets of the winding wheel and the pockets of the tray conveyor. A linear conveyor is disposed downstream of the tray conveyor and box-like items, within the pockets, are circularly conveyed by the continuous rotation of the winding wheel. Packaging sheets are held so as to over the openings of the pockets during the circular conveyance. Thereafter, the pockets of the winding wheel are linearly opposed to the pockets of the continuously moving chain conveyor to deliver the box-like items from the pockets of the chain conveyor whereby the packaging sheets are wound in the shape of U along the surfaces of the box-like items and at the same time one narrow flap at the extended end is folded. Thereafter, both side ends of the packaging sheets, protruding from the pockets, are folded along the outer surfaces of the box-like items and heat-bonded. The other narrow flap, at the extended end, is folded when the box-like items are delivered from the pockets of the chain conveyor to the pockets of the tray conveyor. The box-like items are transferred from the pockets of the tray conveyor to the linear conveyor when the pockets stop, and both wide flaps are successively folded while the box-like items are being horizontally conveyed by the linear conveyor.
However, in this conventional lug folding apparatus for a packaging machine, as described above, the box-like items, continuously conveyed by the pockets of the winding wheel and the pockets of the chain conveyor, are transferred from the pockets of the intermittently rotating tray conveyor to the linear conveyor. This leads to the problem that the operating speed of the tray conveyor cannot be increased, and as a result, the winding wheel and the chain conveyor cannot be operated at high speeds. The processing speed is therefore thusly limited by permitting no increase in speed, thereby failing to provide a large quantity of packages in a short period of time.
Further, the narrow flap at the extended end is merely folded when the box-like item is forced into the pocket, and when the box-like item is extended from the pocket, the once folded flap sometimes returns to its original unfolded state. Particularly, in the case where the packaging sheets are films such as cellophane, polypropylene and so forth, the flap is liable to return to its unfolded state, and results in a defective folding. Thus, there occurs the problem that many defective products are generated.
In view of the above-described prior art shortcomings, it is an object of the present invention to transfer wrapped box-like items, from a continuous circular conveyance to a linear conveyance, without stopping the box-like items. A further object of the present invention is to re-fold a narrow flap after being extended from a pocket.